Earlier this month, defense secretary Robert M. Gates spent a week in East Asia, which has emerged as one of the most vibrant centers of economic growth in the world. Pentagon policymakers tend to use the word "transformation" too loosely, but the Western Pacific is a place where transformation is a very real thing.

Over the last 50 years, China, Japan and South Korea have all ascended to the status of world-class economies, and as they did their societies witnessed profound change. Not surprisingly, U.S. policymakers are devoting more of their time to developments in East Asia.

One recurrent theme in the public remarks of Secretary Gates as he traveled around the region is that local nations, especially Japan, should use their growing wealth to play a more active role in promoting global security. The biggest Asian powers all tend to be somewhat insular by comparison with their European counterparts, even though they are at least as dependent on access to overseas resources and a smoothly functioning trade system. The U.S. Air Force and Navy have increased the tempo of cooperative activities with militaries in the region, but getting local forces to do anything big outside the region is not easy.

Perhaps that is just as well, given China's ambivalence about democracy, South Korea's need to cope with an aberrant cousin to the north, and domestic resistance in Japan to any hint of militarism. But there is still a great deal that the countries can do to foster stability near home, such as restraining North Korea's aggressive impulses and policing sea lanes.

Japan in particular has motivation and potential to do much more, given its high per-capita wealth and technological sophistication. Unfortunately, Washington is sending mixed signals to Tokyo about just how much it really wants the Japanese to do.

A case in point was the recent debate about whether Japan should be permitted to buy the F-22 Raptor fighter, following an expression of interest by a senior Japanese official.

The F-22 is the Air Force's new top-of-the-line fighter, far superior to any other fighter in the world in its agility, survivability and versatility. It's so capable that policymakers aren't inclined to export it, even to trusted allies like Japan. But does that really make sense if Raptor is the plane best suited to protecting the Japanese home islands against cruise-missile attack or preempting a ballistic-missile launch by North Korea?

It sounds like Washington is saying it wants Japan to play a bigger role in regional security, but with inferior weapons -- or that the Japanese will have to depend forever on America to do the really tough missions.

Another case in point is the Air Force's most advanced unmanned reconnaissance aircraft, the Global Hawk. Like F-22, Global Hawk is the most capable aircraft of its kind in the world. It can stay aloft for 36 hours with a 3,000-pound payload of cameras, radars and eavesdropping equipment, far surpassing the persistence of any manned aircraft or satellite in low-earth orbit.

Japan's current inventory of reconnaissance planes consists mainly of older, less capable aircraft, and Global Hawk is well matched to the big distances in the Pacific. Since it's a purely defensive system, why isn't anybody talking about how Global Hawk might fit into the Japanese toolbox of expanded security options? Because it's a little too good to share?

In fairness to the Bush Administration, it has been willing to trust the Japanese with Aegis, the most sophisticated maritime air-defense system in the world. But if we really want the Japanese to be partners in regional security, we should be willing to trust them with other top systems too -- especially since they're the one ally we have that isn't inclined to export weapons.